One so called music accompaniment playing apparatus is referred to as "Karaoke" apparatus. This apparatus is particularly popular in Asian countries such as Japan, Korea, Hong Kong and Taiwan, and is often a part of their home entertainment system. Manufacturers of these "Karaoke" machines are exploring new technologies to enhance their products and differentiate them from competitors in this fast growing market.
FIG. 1 is a block diagram according to the prior art showing the configuration of a "Karaoke" machine 10 which includes a laser video disc musical accompaniment playing apparatus 11. This laser video disc musical accompaniment playing apparatus 11 comprises a laser video disc automatic player for accommodating therein a plurality of laser video discs serving as a musical accompaniment playing information memory medium. The machine 10 includes a controller 12 for controlling the laser video disc automatic player 11 to allow it to select a desired laser video disc 11a. A laser video disc automatic player 11 request is inputted from a user operation input terminal via controller 12. The machine 10 further includes a signal processor 13 including a mixer 13a and amplifiers 13b, left and right speakers 14 for outputting as sound a reproduced audio signal, an image display unit 15 for displaying a reproduced image signal from the video disc as an image, and a microphone 16 for coupling a user's singing voice as input to signal processor 13. The mixer 13a mixes the background audio signal from the laser video disc automatic changer 11, which is a musical signal from the music accompaniment player 11, and the audio signal of a voice singing into the microphone 16, and outputs to speakers 14 via amplifiers 13b.
In accordance with another Karaoke machine the player 11 is a CD automatic changer or audio cassette player for accommodating therein a plurality of compact discs or audio cassettes serving as a musical accompaniment playing information memory medium and reproducing them. The controller 12 controls the CD automatic changer or cassette player to allow it to select the desired compact disc or audio cassette and the CD changer or cassette player by a request inputted from the user input. The signal processor 13 and speakers 14 output and reproduce audio signal as sound. In some embodiments a graphic decoder 15a (in dashed lines) converts graphic data reproduced from a subcode data in the compact disc to an image signal that is displayed on image display 15. A more detailed description of a Karaoke machine may be found in various patents such as U.S. Pat. No. 5,194,682 of Oakamura et al. incorporated herein by reference. In many Karaoke machines, there is a facility for manually changing the "key" or pitch of the background music, so as to match the key of the singer or user. This is done by using a control on the front panel of the Karaoke machine, and involves pressing a push button and/or moving a slider control to go more positive (+) to increase the pitch or more negative (-) to lower the pitch. This feature is referred to as "manual" keying since it requires the user to explicitly depress the button or control and select a pitch. In the prior art there is at least one autokeyer as described in U.S. Pat. No. of 5,296,643 of Kuo et al. In that embodiment the singer's voice is analyzed to determine the singer's voice range.
It is desirable to provide an improved autokeyer (perhaps at a lower cost) where the singer's voice range does not have to be determined.